Why Do I Gain Weight During Marathon Training?

I am training for my first marathon and I am up to 16 miles for my longest run. I am really enjoying the training a lot more than I thought I would. I began training, in large part, because I wanted to lose weight. To my surprise, I have not lost any weight. In fact, I have gained 3 pounds since I started training yet my clothes fit much better. What gives?

Thanks for your help,

Amanda

Dear Amanda-

Welcome to marathon training! Gaining weight while training can happen- you are not alone! Many people think when they take up running, they will lose weight easily, and, in addition, they also think they will be able to lose that weight while eating anything they want. Unfortunately, running doesn't burn as many calories as we would like to think it does. We tend to overestimate our caloric output and underestimate our caloric input.

Consider this, running is purported to burn an average of 100 calories per mile. The problem is the actual caloric expenditure depends upon many factors- it's not a given- and 100 calories is a high estimate for many. A few determining factors are size, weight, running efficiency, muscle mass, run pace, and even the type of run- hills, trail, or road affects the calorie count. In other words, at best, running burns 100 calories a mile. This can lead us to overestimate our caloric needs.

The good news is that your clothes are fitting better! Running is toning and firming up your muscles, making their circumference smaller. At the same time, you are also decreasing your percent body fat, so again, your measurements are smaller. However, muscle tissue is denser than fat tissue and therefore, it weighs more than adipose tissue. Training increases muscle mass to some degree, but it also may tip the scales upward.

Keep in mind that weight is only one measurement. In addition to recording the number on the scale, take your circumference measurements and percent body fat too. Record them to help track your progress. Also, notice how you feel rather than relying solely on numbers.

To minimize the risk of gaining weight while training here are five common training mistakes to look out for:

1) Out-eating your running- It's very easy to overestimate the amount of calories used on a run and underestimate the number of calories consumed. This leads to out-eating our running. It's easy to feel entitled after a long run too. How many times do we say, "I just ran 20 miles, I'm eating anything I want today!"

Suggestion: Keep it real! Individualize the amount of calories you actually used on your run. Use a smart phone app to track the number of calories you burned and to log calories consumed.

2) The Rollercoaster- Long runs can cause our blood sugar levels to go on a rollercoaster ride, especially when using sugary run nutrition products to get through long miles. When blood sugar levels get low, it's hard to make good choices, we just want to eat...immediately! Try eating a small pre-run breakfast rather than starting out on an empty tank to help stabilize blood sugar levels throughout your run. Whole wheat toast and peanut butter or an energy bar are good choices. Experiment with just how much fuel you really need by using it sparingly. For example, try half of a packet at time rather than the full package. A smaller amount may be enough to keep you from hitting the wall, but not enough to cause a huge spike in blood sugar levels.

Suggestion: Keep blood sugar levels as stable as possible. Pack a post-run snack with protein to help end the rollercoaster ride and to nourish your muscles. Protein will help stabilize blood sugar levels while providing nutrients for muscle repair. Try snacks like low-fat chocolate milk, a protein shake, or even a turkey or tuna sandwich.

3) The Incredible Hulk- Add strength training to your fitness routine. Adding muscle boosts your metabolism because it burns calories, while adipose tissue does not, at least not much. Strength training will also improve your running as you create a stronger, more balanced physique. This will also reduce your risk of injury too. And, no worries, you will NOT turn into The Incredible Hulk!

Suggestion: Two times a week hit the gym to lift weights, or do Pilates, or some form of resistance training.

4) Glycogen Stores- Distance training encourages our muscles to increase their storage capacity for glycogen. Having increased glycogen on board is absolutely a necessity to fuel long runs but it can also add some weight. Glycogen also means having additional water on board too so this can also add to the number on the scale.

Suggestion: Use a variety of measurements; don't rely on just the scale to track progress. Circumference measurements and percent body fat are also good fitness tools.

5) Overall Activity Level- Consider your activity level throughout the day. Runners can be couch potatoes in their own way. For example, do you run and then lay on the couch the rest of the day? Or, do you run, then play sports with the kids, do yard work, clean house, and exercise the dog? In other words, how active are you the rest of the day when you are NOT running?

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